System and method for rendering dynamic three-dimensional appearing imagery on a two-dimensional user interface

ABSTRACT

System and method for rendering dynamic three-dimensional appearing imagery on a two-dimensional user interface screen of a portable computing device in dependence on a user&#39;s view-point of the screen. The method includes processing, on a portable computing device, data defining a plurality of user view-points of a user interface screen of the portable computing device. The method next includes rendering a first image of a constructed scene on the user interface screen based on a first determined user&#39;s view-point of the user interface screen of the portable computing device. The method then includes rendering a different image of the constructed scene on the user interface screen based on a subsequently determined user&#39;s view-point of the user interface screen and thereby presenting the illusion of a three-dimensional image of the constructed scene on the user interface screen.

FIELD

This disclosure relates to rendering dynamic three-dimensional imagery,and more particularly to a system and method for rendering dynamicthree-dimensional appearing imagery on a two-dimensional user interfacescreen.

BACKGROUND

Consumers have access to a wide variety of portable electronic devicesthat are generally designed for use by a single person including, forexample, laptop computers, desktop computers, cell phones, and smartphones, among others. These electronic devices frequently contain anembedded camera that can point toward a user of the device. Thesecameras allow the capturing and recording of images or videos by theuser, and sometimes of the user in particular circumstances. Forexample, a camera embedded in a laptop can capture the image (still ordynamic) of a user for display while engaged in video chat orconferencing. In this configuration, participants in a call orconference receive audio data coupled with video data from eachparticipant.

Cameras are also embedded in portable electronic device so that a usercan take pictures, including of him/herself. An example of this is auser taking his or her own picture using the Photo Booth programavailable from Apple, Inc. Further, an operator of an electronic deviceincluding an embedded camera can program the camera to take pictures atspecific time intervals allowing the creation of time-lapse photography.

Portable electronic devices that are generally designed for use by asingle person typically utilize two-dimensional imagery on the userinterface screen. The present disclosure appreciates that the provisionof three-dimensional images on the user interface screens would alsoprovide a benefit. In order to make these three-dimensional images moreengaging, it has also been appreciated that if the user were able to“look around” the image, those images would be considered moreinteresting. That is to say, if the user is looking at a 3D image of asculpture on the user interface screen, for instance, and desired tolook at the right side (relative to the user) of the displayedsculpture, it would be of great interest to the user for the image ofthat right side of the sculpture to be displayed on cue by the user. Inthis context, if the actual sculpture was being observed and the userwanted to view its right side, the user would move their head to theright and peer left. The present disclosure capitalizes on this naturalbehavior and governs the presentation of images based on the relativeposition and orientation of the users head and/or eyes relative to theuser interface screen when three-dimensional appearing images are beingdisplayed.

SUMMARY

Additional features and advantages of the disclosure will be set forthin the description which follows, and in part will be obvious from thedescription, or may be learned through the practice of what is taught.The features and advantages of the disclosure may be realized andobtained by means of the instruments and combinations particularlypointed out in the patented claims. These and other features will becomemore fully apparent from the following description and the patentedclaims, or may be learned by the practice of that which is described.

This disclosure describes a system and method for rendering dynamicthree-dimensional appearing imagery on a two-dimensional user interfacescreen. Disclosed are systems, methods and computer readable media forrendering such three-dimensional appearing imagery based on a user'sview-point of the screen. In a most basic sense, the present systempresents images in a way that mimics what a viewer sees in the realworld when viewing an object. Using the example above of viewing asculpture, if instead of viewing the actual sculpture, the user wasviewing images of the sculpture on the user interface screen, thepresent system and method presents corresponding images to what would beseen if the user moved his head about the actual object, but in thiscase he/she moves his/her head relative to the view screen. The positionand orientation of the head/eyes of the viewer relative to the viewscreen is assessed and images are presented on the view screen incorrespondence therewith.

Therefore, using the sculpture example again, if the viewer positionshis/her head above and to the right relative to the view screen, even ifever so slightly, this will be detected using head or eye trackingfeatures on the device and an image will be presented on the view screenthat represents the top, right perspective view down onto the sculpture.In this manner the user can easily control the display of dynamicthree-dimensional appearing images in a very natural way. By just movingyour head toward or to the position relative to the view screen fromwhich you would like to see the displayed object, a correspondingthree-dimensional appearing image of the object from that perspectivewill be displayed. The display is considered dynamic in that theeyes/head are constantly being tracked and series of images can berendered on the screen that make it appear to the viewer that he isnaturally seeing continuously different perspectives of the viewedobject just by moving the head/eyes relative the screen in what isalready the most natural of ways.

Aspects of the method disclosed herein and the principles associatedtherewith are also applicable to the system and computer readable mediumembodiments that are also described. Accordingly, a method for renderingdynamic three-dimensional appearing imagery on a two-dimensional userinterface screen of a portable computing device in dependence on auser's view-point of the screen is disclosed. The method includesprocessing, on a portable computing device, data defining a plurality ofuser view-points of a user interface screen of the portable computingdevice. The method next includes rendering a first image of aconstructed scene on the user interface screen based on a firstdetermined user's view-point of the user interface screen of theportable computing device. The method then includes rendering adifferent image of the constructed scene on the user interface screenbased on a subsequently determined user's view-point of the userinterface screen and thereby presenting the illusion of athree-dimensional image of the constructed scene on the user interfacescreen.

The data defining the plurality of user view-points of the userinterface screen of the portable computing device can be at leastpartially acquired from signals received from a camera associated withthe portable computing device.

The data processing can include determining a position of a user's headrelative to the user interface screen. The data processing can furtherinclude determining a position of a user's pair of eyes relative to theuser interface screen. The data processing can also include determininga position and orientation relative to, and a distance from the userinterface screen of a user's head. The data processing can also includedetermining a position and orientation relative to, and a distance fromthe user interface screen of a user's pair of eyes.

The camera, as described above, can be located on the portable computingdevice. The camera can also be positioned on the portable computingdevice at a fixed location relative to the user interface screen. Thecamera can also include infrared sensitivity for sensing infraredimages.

The method for rendering dynamic three-dimensional appearing imagery, asdescribed above, can include emitting infrared light at the portablecomputing device away from the user interface screen. The method canalso include acquiring, from signals received from a camera associatedwith the portable computing device, the data defining the plurality ofuser view-points of the user interface screen of the portable computingdevice based on infrared images of a user observing the screen. Themethod can also include processing the data acquired from the signalsreceived from the camera to determine user eye position relative to theuser interface screen of the portable computing device.

The infrared light can emanate from an infrared light emitter locatedproximate the camera on the portable computing device.

Additionally, the method can include processing the data acquired fromthe signals received from the camera to determine user head positionrelative to the user interface screen of the portable computing device.The portable computing device can be a personal digital assistant.

The portable computing device can be wireless enabled and theconstructed scene can be wirelessly received by the portable computingdevice from a remote source prior to the different images displayed onthe user interface screen being rendered locally on the portablecomputing device.

The data defining a plurality of user view-points of the user interfacescreen of the portable computing device can be limited to datarepresentative of a single user of the portable computing device.

The infrared light emitter can be an infrared light emitting diode. Thisemitter can be embedded in the portable electronic device.

The camera can utilize, for example, a charge coupled device (CCD) orcomplementary metal oxide semiconductor (CMOS) microchip to detectimages. However, the method applies to any portable computing device orcombination of devices that allow rendering dynamic three-dimensionalappearing imagery on a two-dimensional user interface screen of aportable computing device in dependence on a user's view-point of thescreen.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the advantages and features ofthis disclosure can be obtained, a more particular description isprovided below, including references to specific embodiments which areillustrated in the appended drawings. Understanding that these drawingsdepict only exemplary embodiments and are not therefore to be consideredlimiting, the subject matter will be described and explained withadditional specificity and detail through the use of the accompanyingdrawings in which:

FIG. 1 illustrates an example system embodiment;

FIG. 2 illustrates an example portable computing device;

FIG. 3 illustrates an example method embodiment; and

FIG. 4 illustrates another method embodiment.

DETAILED DESCRIPTION

Various example embodiments of the rendering of three-dimensionalappearing imagery are described in detail below. While specificimplementations are discussed, it should be understood that this is donefor illustration purposes only. A person skilled in the relevant artwill recognize that other components and configurations may be usedwithout parting from the spirit and scope of the disclosure.

Non-contact optical methods for measuring eye position and motiontypically involve sensing reflected infrared light. This reflectedinfrared light is reflected from a user's face but absorbed by a user'spupils. Therefore, the points of light absorbtion can be detected aseyes. Alternatively, the IR data can be inverted, and then the pupilswill stand out as very bright circles. The sensing can be done by acamera or other image sensing device. Camera based eye trackerstypically use the corneal reflection (also known as the first Purkinjeimage) and the center of the pupil as features to track over time. Amore sensitive type of eye tracker, the dual-Purkinje eye tracker, usesreflections from the front of the cornea (first Purkinje image) and theback of the lens (the fourth Purkinje image) as features to track. Aneven more sensitive method of eye tracking is to sense image featureswithin the eye, such as the retinal blood vessels, and follow thesefeatures as the eye rotates. However, any method for tracking headposition and eye position of a person using a personal computing deviceis contemplated as within the scope of this disclosure. Also, otherfeatures of a user, such as nose, chin, or ears can be utilized fortracking a user's head position for rendering the appropriatethree-dimensional appearing imagery. These alternate features can betracked when it is not possible to track the user's eyes.

Accelerometer(s) or similar type motion sensors can be incorporated intohandheld device versions of the system to assist the tracking ofrelative head position as the device is moved about in comparison to theuser's head and eyes. This routine is based on the premise that therelatively small handheld device will normally be held in the hand andmoved about the user instead of the user moving his or her head aboutthe device. In this variation, after initial target acquisition, thedevice relies on continual input from the accelerometer(s) and thenperiodically uses a camera to capture infrared images to track a user'seyes and/or head for rendering three-dimensional appearing imagery.Correspondingly, the method can include reading data from the motionsensors in coordination with reading data from the camera for renderingthe three-dimensional appearing imagery. Among other benefits, use ofthe accelerometer(s) in tandem with the camera permits less overallpower consumption and manipulation of the data outputted by theaccelerometer(s) is computationally less expensive and more performantthan the camera alone.

With reference to FIG. 1, an exemplary system includes a general-purposecomputing device 100, including a processing unit (CPU) 120 and a systembus 110 that couples various system components including the systemmemory such as read only memory (ROM) 140 and random access memory (RAM)150 to the processing unit 120. Other system memory 130 may be availablefor use as well. It can be appreciated that the program may operate on acomputing device with more than one CPU 120 or on a group or cluster ofcomputing devices networked together to provide greater processingcapability. The system bus 110 may be any of several types of busstructures including a memory bus or memory controller, a peripheralbus, and a local bus using any of a variety of bus architectures. Abasic input/output (BIOS) stored in ROM 140 or the like, may provide thebasic routine that helps to transfer information between elements withinthe computing device 100, such as during start-up.

The computing device 100 further includes storage devices such as a harddisk drive 160, a magnetic disk drive, an optical disk drive, tape driveor the like. The storage device 160 is connected to the system bus 110by a drive interface. The drives and the associated computer readablemedia provide nonvolatile storage of computer readable instructions,data structures, program modules and other data for the computing device100. The basic components are known to those of skill in the art andappropriate variations are contemplated depending on the type of device,such as whether the device is a small, handheld computing device, adesktop computer, or a computer server.

Although the exemplary environment described herein employs the harddisk, it should be appreciated by those skilled in the art that othertypes of computer readable media which can store data that areaccessible by a computer, such as magnetic cassettes, flash memorycards, digital versatile disks, cartridges, random access memories(RAMs), read only memory (ROM), a cable or wireless signal containing abit stream and the like, may also be used in the exemplary operatingenvironment.

To enable user interaction with the computing device 100, an inputdevice 190 represents any number of input mechanisms, such as amicrophone for speech, a touch-sensitive screen for gesture or graphicalinput, keyboard, mouse, motion input, speech and so forth. The deviceoutput 170 can also be one or more of a number of output mechanismsknown to those of skill in the art. In some instances, multimodalsystems enable a user to provide multiple types of input to communicatewith the computing device 100. The communications interface 180generally governs and manages the user input and system output. There isno restriction requiring operation on any particular hardwarearrangement and therefore the basic features here may easily besubstituted for improved hardware or firmware arrangements as they aredeveloped.

For clarity of explanation, the illustrative system embodiment ispresented as comprising (including, but not limited to) individualfunctional blocks (including functional blocks labeled as a“processor”). The functions these blocks represent may be providedthrough the use of either shared or dedicated hardware, including, butnot limited to, hardware capable of executing software. For example thefunctions of one or more processors presented in FIG. 1 may be providedby a single shared processor or multiple processors. (Use of the term“processor” should not be construed to refer exclusively to hardwarecapable of executing software.) Illustrative embodiments may comprisemicroprocessor and/or digital signal processor (DSP) hardware, read-onlymemory (ROM) for storing software performing the operations discussedbelow, and random access memory (RAM) for storing results. Very largescale integration (VLSI) hardware embodiments, as well as custom VLSIcircuitry in combination with a general purpose DSP circuit, may also beprovided.

As noted above, the present disclosure enables the rendering ofthree-dimensional appearing imagery on a two-dimensional user interfacescreen of a portable computing device. Any portable computing devicecapable of rendering such three-dimensional appearing imagery based on auser's view of the screen is contemplated as within the scope and spiritof this disclosure. Also, any camera, including a camera capable ofsensing infrared light, is contemplated as within the scope of thisdisclosure.

FIG. 2 illustrates an example portable computing device 200. The device,for example, can be a phone, PDA, personal entertainment device, laptopcomputer, or desktop computer. The device 200 also includes a body 210and a display 220. The display 220 can be a LCD (liquid crystaldisplay). The device 200 includes a camera 230. The camera 230 can be aCCD (charge coupled device) which is sensitive to infrared as well asvisible light. Other light sensing technologies, such as CMOS(complementary metal oxide semiconductor), can be used as well. Thecamera 230 is positioned in a fixed position relative to the display220. The camera 230 is positioned to face towards a user interactingwith the device 200. The camera 230 can have other uses than acquiringdata to determine a plurality of user view-points of the display 220.For example, the camera's 230 primary use can be for video conferencing.

Two infrared light emitters 240 are positioned on the device 200 asshown. Other embodiments can include one or more infrared lightemitters. The infrared light emitters 240, as shown in FIG. 2, can below-power LEDs (light emitting diodes). These infrared light emitterscan be housed or sealed in the body 210 of the device 200 so that theyare not noticeable during normal use.

The camera 230 and infrared light emitters 240 should be positioned sothat a user will not typically block them while using the features ofthe invention during normal operation.

When the device 200 of FIG. 2 is active, the infrared emitters 240produce infrared light aimed at a user. The infrared light is invisibleto the naked human eye. The camera 230 captures images of a user. Thedevice 200 determines a head position target (HPT). The device 200determines the location of the user's eyes by analyzing reflection andabsorption patterns in the infrared spectrum.

Human eyes have a well characterized size and absorption pattern. Thepupils of the eyes will appear clearly as a pair of light absorbingcircles which remain a fixed distance from each other. Human pupils havea generally well-defined range of size and distance. They periodicallydisappear and reappear as the eyes blink. This makes pupils of eyesideal to identify and track using image recognition software.

Turning back to FIG. 2, the device shown determines the user's eyesrelative position in comparison to the camera 230. In the event that theuser's pupils are obscured, (for example if the user is wearingreflective glasses) an alternate signature target can be used andcalculated. The device will usually be able to continue rendering thethree-dimensional appearing imagery based on this alternate signaturetarget.

From this pupil data, or alternate signature target data, a user'slikely head position, orientation, and distance from the display 220 canbe calculated. If the system determines that insufficient information ispresent to identify the relative location of the user (e.g., 2 “eyes”cannot be identified, or multiple users are using the device, or thecamera or IR emitters are obscured or not operating) the device 200 candefault to a mode presenting a standard 2-dimensional display. However,other modes can be programmed into the device so that other functionsoccur when there is insufficient information present to identify therelative location of the user's head.

Using the collected head position information, the device 200 canconstruct and display a three-dimensional appearing scene. Among otherthings (essentially anything), this scene can correspond to a graphicaluser interface being displayed on the device 200 to a user. Thepresented view of this virtual scene is determined by the user's currenthead position. As frames of the scene are rendered, the displayed imageis adjusted in accordance to the actual user's head position relative tothe screen 220 of the device 200.

The result is an illusion or virtual perspective which, to the userbeing tracked, makes the images rendered on the display appear dynamicand three-dimensional. This virtual perspective can be maintained aslong as the stream of data regarding the user's head position ismaintained and is determined to be reliable. As the user's head movesrelative to the device, the invention repositions the virtual camera tomaintain a continuous illusion. If, at some point, the user's headposition cannot be calculated, the system will fall back into a “targetacquisition” mode and attempt to relocate the user and reestablish thevirtual perspective.

Having discussed the example portable computing device of FIG. 2, thepresent description turns to the exemplary method embodiment that isdescribed. FIG. 3 charts an example of the method.

Accordingly, a method for rendering dynamic three-dimensional appearingimagery on a two-dimensional user interface screen of a portablecomputing device in dependence on a user's view-point of the screen isshown in FIG. 3. The method includes processing, on a portable computingdevice, data defining a plurality of user view-points of a userinterface screen of the portable computing device 302. The method nextincludes rendering a first image of a constructed scene on the userinterface screen based on a first determined user's view-point of theuser interface screen of the portable computing device 304. The methodthen includes rendering a different image of the constructed scene onthe user interface screen based on a subsequently determined user'sview-point of the user interface screen and thereby presenting theillusion of a three-dimensional image of the constructed scene on theuser interface screen 306. This process is continuously repeated therebypresenting a seemingly dynamic three dimensional image of the scene forthe user, and which can be adapted by the user simply changing his orher view point of the user interface screen.

The data defining the plurality of user view-points of the userinterface screen of the portable computing device can be at leastpartially acquired from signals received from a camera associated withthe portable computing device. As mentioned above, the camera can be acharge coupled device (CCD) or complementary metal oxide semiconductor(CMOS) microchip. Other camera technologies can be used as well.

The data processing can include determining a position of a user's headrelative to the user interface screen. The data processing can furtherinclude determining a position of a user's pair of eyes relative to theuser interface screen. The data processing can also include determininga position and orientation relative to, and a distance from the userinterface screen of a user's head. The data processing can also includedetermining a position and orientation relative to, and a distance fromthe user interface screen of a user's pair of eyes.

The camera, as described above, can be located on the portable computingdevice. The camera can also be positioned on the portable computingdevice at a fixed location relative to the user interface screen. Thecamera can also include infrared sensitivity for sensing infraredimages.

The method for rendering dynamic three-dimensional appearing imagery, asdescribed above, can include emitting infrared light at the portablecomputing device away from the user interface screen. In one embodimentinfrared LEDs (light emitting diodes) are incorporated into the body ofthe portable computing device. The method can also include acquiring,from signals received from a camera associated with the portablecomputing device, the data defining the plurality of user view-points ofthe user interface screen of the portable computing device based oninfrared images of a user observing the screen. The method can alsoinclude processing the data acquired from the signals received from thecamera to determine user eye position relative to the user interfacescreen of the portable computing device.

The infrared light can emanate from an infrared light emitter locatedproximate the camera on the portable computing device.

Additionally, the method can include processing the data acquired fromthe signals received from the camera to determine user head positionrelative to the user interface screen of the portable computing device.The portable computing device can be a personal digital assistant.

The portable computing device can be wireless enabled and theconstructed scene can be wirelessly received by the portable computingdevice from a remote source prior to the different images displayed onthe user interface screen being rendered locally on the portablecomputing device.

The data defining a plurality of user view-points of the user interfacescreen of the portable computing device can be limited to datarepresentative of a single user of the portable computing device.

The infrared light emitter can be an infrared light emitting diode. Thisemitter can be embedded in the portable electronic device.

FIG. 4 illustrates another method embodiment for renderingthree-dimensional appearing imagery. The system determines if the cameraand IR (infrared emitters) are active 402. If no, the system disablesthe rendering of three-dimensional appearing imagery 412 and displaystwo-dimensional appearing imagery.

If the camera and IR are active the system determines if there is alikely target 404. If no, the system disables the rendering ofthree-dimensional appearing imagery 412 and displays two-dimensionalappearing imagery.

If there is a likely target, the system determines if the naked eye HPT(head position target) analyzer is able to determine the user's eyesrelative position in comparison to a camera 406. If no, an alternatesignature target can be used and calculated 408. This failure todetermine the user's eyes relative position in comparison to a cameracan occur when the user's pupils are obscured, (For example if the useris wearing reflective glasses). The system will usually be able tocontinue rendering the three-dimensional appearing imagery based on thisalternate signature target found using alternate HPT analyzer 408.

If the naked eye HPT (head position target) analyzer is able todetermine the user's eyes relative position in comparison to a camera,the system constructs a virtual scene 410. The system then places avirtual camera 414. This determines the point of view that should bedisplayed to a user to render the three-dimensional appearing imagery.The system then renders a scene 416. The system then determines if theHPT (head position target) has been lost 418. If the HPT has not beenlost, the system refreshes and goes back for another cycle of the nakedeye HPT analyzer 406.

If the HPT (head position target) has been lost, the system goes back todetermining if there is a likely target 404 and proceeding to the nextstep once a likely target is identified.

Embodiments within the scope of the present disclosure may also includecomputer-readable media for carrying or having computer-executableinstructions or data structures stored thereon. Such computer-readablemedia can be any available media that can be accessed by a generalpurpose or special purpose computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium which can be used to carryor store desired program code means in the form of computer-executableinstructions or data structures. When information is transferred orprovided over a network or another communications connection (eitherhardwired, wireless, or combination thereof) to a computer, the computerproperly views the connection as a computer-readable medium. A“tangible” computer-readable medium expressly excludes software per se(not stored on a tangible medium) and a wireless, air interface. Thus,any such connection is properly termed a computer-readable medium.Combinations of the above should also be included within the scope ofthe computer-readable media.

Computer-executable instructions include, for example, instructions anddata that cause a general purpose computer, special purpose computer, orspecial purpose processing device to perform a certain function or groupof functions. Computer-executable instructions also include programmodules that are executed by computers in stand-alone or networkenvironments. Generally, program modules include routines, programs,objects, components, and data structures and the like that performparticular tasks or implement particular abstract data types.Computer-executable instructions, associated data structures, andprogram modules represent examples of the program code means forexecuting steps of the methods disclosed herein. The particular sequenceof such executable instructions or associated data structures representsexamples of corresponding acts for implementing the functions describedin such steps. Program modules may also comprise any tangiblecomputer-readable medium in connection with the various hardwarecomputer components disclosed herein, when operating to perform aparticular function based on the instructions of the program containedin the medium.

Those of skill in the art will appreciate that other embodiments of thisdisclosure may be practiced in network computing environments with manytypes of computer system configurations, including personal computers,hand-held devices, multi-processor systems, microprocessor-based orprogrammable consumer electronics, network PCs, minicomputers, and thelike. Embodiments may also be practiced in distributed computingenvironments where tasks are performed by local and remote processingdevices that are linked (either by hardwired links, wireless links, orby a combination thereof) through a communications network. In adistributed computing environment, program modules may be located inboth local and remote memory storage devices.

Although the above description may contain specific details, they shouldnot be construed as limiting the claims in any way. Other configurationsof the described embodiments are part of the scope of this disclosure.Accordingly, the patented claims and their legal equivalents shall onlydefine the invention(s), rather than any specific examples describedherein.

1. A method for rendering dynamic three-dimensional appearing imagery ona two-dimensional user interface screen of a portable computing devicein dependence on a user's view-point of the screen, said methodcomprising: processing, on a portable computing device, data defining aplurality of user view-points of a user interface screen of the portablecomputing device; rendering a first image of a constructed scene on theuser interface screen based on a first determined user's view-point ofthe user interface screen of the portable computing device; andrendering a different image of the constructed scene on the userinterface screen based on a subsequently determined user's view-point ofthe user interface screen and thereby presenting the illusion of athree-dimensional image of the constructed scene on the user interfacescreen.
 2. The method as recited in claim 1, wherein the data definingthe plurality of user view-points of the user interface screen of theportable computing device is at least partially acquired from signalsreceived from a camera associated with the portable computing device. 3.The method as recited in claim 2, wherein said data processing furthercomprises determining a position of a user's head relative to the userinterface screen.
 4. The method as recited in claim 2, wherein said dataprocessing further comprises determining a position of a user's pair ofeyes relative to the user interface screen.
 5. The method as recited inclaim 2, wherein said data processing further comprises determining aposition and orientation relative to, and a distance from the userinterface screen of a user's head.
 6. The method as recited in claim 2,wherein said data processing further comprises determining a positionand orientation relative to, and a distance from the user interfacescreen of a user's pair of eyes.
 7. The method as recited in claim 2,wherein the camera is located on the portable computing device.
 8. Themethod as recited in claim 7, wherein the camera is positioned on theportable computing device at a fixed location relative to the userinterface screen.
 9. The method as recited in claim 8, wherein thecamera has infrared sensitivity for sensing infrared images.
 10. Themethod as recited in claim 1, further comprising emitting infrared lightat the portable computing device away from the user interface screen.11. The method as recited in claim 10, further comprising acquiring,from signals received from a camera associated with the portablecomputing device, the data defining the plurality of user view-points ofthe user interface screen of the portable computing device based oninfrared images of a user observing the screen.
 12. The method asrecited in claim 11, further comprising processing the data acquiredfrom the signals received from the camera to determine user eye positionrelative to the user interface screen of the portable computing device.13. The method as recited in claim 12, wherein the infrared lightemanates from an infrared light emitter located proximate the camera onthe portable computing device.
 14. The method as recited in claim 11,further comprising processing the data acquired from the signalsreceived from the camera to determine user head position relative to theuser interface screen of the portable computing device.
 15. The methodas recited in claim 1, wherein the portable computing device is apersonal digital assistant.
 16. The method as recited in claim 1,wherein the portable computing device is wireless enabled and theconstructed scene is wirelessly received by the portable computingdevice from a remote source prior to the different images displayed onthe user interface screen being rendered locally on the portablecomputing device.
 17. The method as recited in claim 1, wherein the datadefining a plurality of user view-points of the user interface screen ofthe portable computing device is limited to data representative of asingle user of the portable computing device.
 18. A system for renderingdynamic three-dimensional appearing imagery on a two-dimensional userinterface screen of a portable computing device in dependence on auser's view-point of the screen, said method comprising: a module toprocess, on a portable computing device, data defining a plurality ofuser view-points of a user interface screen of the portable computingdevice; a module to render a first image of a constructed scene on theuser interface screen based on a first determined user's view-point ofthe user interface screen of the portable computing device; and a moduleto render a different image of the constructed scene on the userinterface screen based on a subsequently determined user's view-point ofthe user interface screen and thereby presenting the illusion of athree-dimensional image of the constructed scene on the user interfacescreen.
 19. The system as recited in claim 18, wherein the data definingthe plurality of user view-points of the user interface screen of theportable computing device is at least partially acquired from signalsreceived from a camera associated with the portable computing device.20. The system as recited in claim 19, wherein said data processingmodule further comprises a module to determine a position of a user'shead relative to the user interface screen.
 21. The system as recited inclaim 19, wherein said data processing module further comprises a moduleto determine a position of a user's pair of eyes relative to the userinterface screen.
 22. The system as recited in claim 19, wherein saiddata processing module further comprises a module to determine aposition and orientation relative to, and a distance from the userinterface screen of a user's head.
 23. The system as recited in claim19, wherein said data processing module further comprises a module todetermine a position and orientation relative to, and a distance fromthe user interface screen of a user's pair of eyes.
 24. The system asrecited in claim 19, wherein the camera is located on the portablecomputing device.
 25. The system as recited in claim 20, wherein thecamera is positioned on the portable computing device at a fixedlocation relative to the user interface screen.
 26. The system asrecited in claim 25, wherein the camera has infrared sensitivity forsensing infrared images.
 27. The system as recited in claim 18, furthercomprising a module to emit infrared light at the portable computingdevice away from the user interface screen.
 28. The system as recited inclaim 27, further comprising a module to acquire, from signals receivedfrom a camera associated with the portable computing device, the datadefining the plurality of user view-points of the user interface screenof the portable computing device based on infrared images of a userobserving the screen.
 29. The system as recited in claim 28, furthercomprising a module to process the data acquired from the signalsreceived from the camera to determine user eye position relative to theuser interface screen of the portable computing device.
 30. The systemas recited in claim 29, wherein the infrared light emanates from aninfrared light emitter located proximate the camera on the portablecomputing device.
 31. The system as recited in claim 28, furthercomprising a module to process the data acquired from the signalsreceived from the camera to determine user head position relative to theuser interface screen of the portable computing device.
 32. The systemas recited in claim 18, wherein the portable computing device is apersonal digital assistant.
 33. The system as recited in claim 18,wherein the portable computing device is wireless enabled and theconstructed scene is wirelessly received by the portable computingdevice from a remote source prior to the different images displayed onthe user interface screen being rendered locally on the portablecomputing device.
 34. The system as recited in claim 18, wherein thedata defining a plurality of user view-points of the user interfacescreen of the portable computing device is limited to datarepresentative of a single user of the portable computing device.
 35. Atangible computer-readable medium storing instructions for categorizingdigital media based on calendar events, the instructions comprising:processing, on a portable computing device, data defining a plurality ofuser view-points of a user interface screen of the portable computingdevice; rendering a first image of a constructed scene on the userinterface screen based on a first determined user's view-point of theuser interface screen of the portable computing device; and rendering adifferent image of the constructed scene on the user interface screenbased on a subsequently determined user's view-point of the userinterface screen and thereby presenting the illusion of athree-dimensional image of the constructed scene on the user interfacescreen.